1. Field of the Invention
The present invention relates to a pneumatic actuator, and more particularly, to a pneumatic actuator system and method.
2. Statement of the Problem
An actuator is a device that performs some mechanical action. One actuator is a piston, wherein a plunger of the piston moves in a reciprocating manner. The plunger can therefore be connected to some manner of work piece or other mechanical system.
In some actuator applications, it is desirable to have more than one actuation speed and/or more than one actuation force over the range of motion of the actuator. For example, in a spot welder machine, a pair of welding jaws must be brought together onto a work piece during a welding operation. The jaws must clamp onto the work piece with a desired force. Therefore, at the end of a clamping motion range, a relatively high actuation force must be provided to the welding jaws.
However, an actuator that provides a high level of force typically provides a relatively small range of actuation travel. This can be a problem where the jaws of the spot welder machine must open wide in order to be positioned on the work piece. Therefore, a jaw actuator of the spot welder machine needs to move relatively rapidly during a first actuation span and a large force is not required. During the second actuation span, the jaws need to move only a small distance, but must be able to provide a large clamping force.
An actuator for a machine typically requires precise control, with a minimum of slop. The need may be greater for a two-phase actuator having a first actuation phase followed by a second actuation phase, wherein the first actuation phase covers a greater actuation span at a greater speed but offers less force. The subsequent second actuation phase has a small actuation span and a lesser speed but offers a greater actuation force.
However, there are many other machines or devices that employ pneumatic actuators. Consequently, there is a need to flexibly control an actuation speed, force, and/or distance. There may additionally be a need to implement a custom actuation profile.
In addition, in a machine that includes an actuator, the machine will inevitably wear and degrade over time. This will lead to increased resistance in the machine. Therefore, there is a need for an actuator that can compensate for wear or other changes in operational conditions.